org.hibernate.LazyInitializationException: could not initialize proxy - no Session

今天在写jbpm获取流程变量的时候出现了这个异常：org.hibernate.LazyInitializationException: could not initialize proxy - no Session
原因就是jbpm的底层采用了懒加载的方式，解决这个异常的方法就是在对象的映射文件中去掉默认的懒加载，例如：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="cn.itcast.jbpm.processVariable.Form" table="itcast_form" lazy="false">
        <id name="id" type="long">
            <column name="id"></column>
            <generator class="increment"></generator>
        </id>
        <property name="title" type="string">
            <column name="title"></column>
        </property>
    </class>
</hibernate-mapping>
方法一：lazy默认是true，改成false就不会出现该异常了。

方法二：就是把这个类改成final类型的，这样它就不会产生代理对象了，如下：
package cn.itcast.jbpm.processVariable;

public final class Form {

  private Long id;
  private String title;
  
  public Form(){
    
  }

  public Form(Long id, String title) {
    this.id = id;
    this.title = title;
  }

  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public String getTitle() {
    return title;
  }

  public void setTitle(String title) {
    this.title = title;
  }
}